linux-kernel - Re: [PATCH] ovl: warn if trusted xattr creation fails

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Date:   Sat, 26 Feb 2022 19:15:50 +0100
From:   Alois Wohlschlager <alwoju@....de>
To:     Miklos Szeredi <miklos@...redi.hu>
Cc:     linux-unionfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ovl: warn if trusted xattr creation fails

Am Montag, 21. Februar 2022, 12:11:47 CET schrieb Miklos Szeredi:
>
> Thanks for the patch.
>
> How about the following (untested) variant?
>
> Thanks,
> Miklos
>
>
> diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
> index 7bb0a47cb615..955aeefc3b29 100644
> --- a/fs/overlayfs/super.c
> +++ b/fs/overlayfs/super.c
> @@ -1413,11 +1413,12 @@ static int ovl_make_workdir(struct super_block *sb,
> struct ovl_fs *ofs, */
>  	err = ovl_do_setxattr(ofs, ofs->workdir, OVL_XATTR_OPAQUE, "0", 1);
>  	if (err) {
> +		pr_warn("failed to set xattr on upper\n");
>  		ofs->noxattr = true;
>  		if (ofs->config.index || ofs->config.metacopy) {
>  			ofs->config.index = false;
>  			ofs->config.metacopy = false;
> -			pr_warn("upper fs does not support xattr, falling back to
> index=off,metacopy=off.\n"); +			pr_warn("...falling back to
> index=off,metacopy=off.\n");
>  		}
>  		/*
>  		 * xattr support is required for persistent st_ino.
> @@ -1425,8 +1426,10 @@ static int ovl_make_workdir(struct super_block *sb,
> struct ovl_fs *ofs, */
>  		if (ofs->config.xino == OVL_XINO_AUTO) {
>  			ofs->config.xino = OVL_XINO_OFF;
> -			pr_warn("upper fs does not support xattr, falling back to xino=off.\n");
> +			pr_warn("...falling back to xino=off.\n");
>  		}
> +		if (err == -EPERM && !ofs->config.userxattr)
> +			pr_info("try mounting with 'userxattr' option\n");
>  		err = 0;
>  	} else {
>  		ovl_do_removexattr(ofs, ofs->workdir, OVL_XATTR_OPAQUE);

Seems sensible to me, since it doesn't duplicate information in case index, metacopy or xino are attempted to be used.

Alois